It is conventional for most automatic car wash systems to include some sort of wheel washer; i.e., a device which sprays a cleaning fluid onto the wheels of a passing vehicle moving along a car wash path of travel defined, for example, by a car wash conveyor. Most wheel washers are stationary devices, a factor which limits the exposure of the passing vehicle wheels to the cleaning fluids. A wheel washer which moves with the vehicle a short distance is known. This device includes a small dolly and the power to move it is provided by the vehicle being washed. Installation is complex.